GoogleContainerTools/skaffold · error

evaluating custom template component: %w

Error message

evaluating custom template component: %w

What it means

One of the component taggers failed while generating its tag string during custom template evaluation. After all taggers are collected, `EvaluateComponents` calls each tagger's `GenerateTag(ctx, image)`; any failure is wrapped with this message naming none of them directly but wrapping the underlying cause. The template is never executed.

Source

Thrown at pkg/skaffold/tag/custom_template.go:101

			gitTagger, _ := NewGitCommit("", "", false)
			taggers[field] = gitTagger
		case "DATE":
			taggers[field] = NewDateTimeTagger("", "")
		case "SHA":
			taggers[field] = &ChecksumTagger{}
		case "INPUT_DIGEST":
			inputDigestTagger, _ := NewInputDigestTagger(t.RunCtx, graph.ToArtifactGraph(t.RunCtx.Artifacts()))
			taggers[field] = inputDigestTagger
		default:
			return nil, fmt.Errorf("no tagger available for component %+v", field)
		}
	}

	customMap := map[string]string{}
	for k, v := range taggers {
		tag, err := v.GenerateTag(ctx, image)
		if err != nil {
			return nil, fmt.Errorf("evaluating custom template component: %w", err)
		}
		customMap[k] = tag
	}
	return customMap, nil
}

// ParseCustomTemplate is a simple wrapper to parse an custom template.
func ParseCustomTemplate(t string) (*template.Template, error) {
	return template.New("customTemplate").Parse(t)
}

// ExecuteCustomTemplate executes a customTemplate against a custom map.
func ExecuteCustomTemplate(customTemplate *template.Template, customMap map[string]string) (string, error) {
	var buf bytes.Buffer
	log.Entry(context.TODO()).Debugf("Executing custom template %v with custom map %v", customTemplate, customMap)
	if err := customTemplate.Execute(&buf, customMap); err != nil {
		return "", fmt.Errorf("executing template: %w", err)
	}

View on GitHub (pinned to a1189de023)

Solutions

1. Read the wrapped cause to identify which component failed and why
2. For GIT component: ensure the workspace is a git repo with at least one commit (git init && git commit)
3. For DIGEST/SHA components: ensure the image was built/pushed before tagging
4. Verify git is installed and accessible on PATH

Example fix

// before: not a git repo, GIT tagger fails
skaffold dev
// after
git init && git add -A && git commit -m init
skaffold dev

// pre-check environment for GIT component
if fieldsContain(tmpl, "GIT") {
    if _, err := exec.LookPath("git"); err != nil {
        return errors.New("git not on PATH; required by GIT tag component")
    }
    if _, err := git.ExecCommand(ctx, nil, "rev-parse", "HEAD"); err != nil {
        return errors.New("not a git repository with commits")
    }
}

customMap, err := tag.EvaluateComponents(ctx, t, image)
if err != nil {
    var cause error
    if errors.As(err, &cause) {
        log.Errorf("component failed: %v", cause) // e.g. git describe error
    }
    return fmt.Errorf("ensure git repo exists and image is built: %w", err)
}

When it happens

Trigger: During `GenerateTag`, a component tagger (e.g. GIT, SHA, DIGEST) errors — e.g. `git describe` fails because the workspace is not a git repo, or digest computation fails because the image isn't available.

Common situations: GIT component used outside a git repository or with no commits; SHA/digest tagger used before the image is built/pushed; git binary missing in the environment; shallow clone without tags.

Related errors

• getting tags: %w
• parsing template: %w
• no tagger available for component %+v
• executing template: %w
• %q is not a valid git tagger variant

AI-assisted analysis of GoogleContainerTools/skaffold@a1189de023 (2026-09-05). Data as JSON: /api/errors/fe1b3f7add827ea9. Report an issue: GitHub.